Telegraphophone



Feb. 9, 1932. LE ROY J. LEISHMAN TELEGRAPHOPHONE Filed Oct. 6. 1927 ls: AUDIO g'nvwnio'o LeRo yJL Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE LE ROY J. LEISHMAN, LOS ANGELES, CALIFORNIA rnnnenarnornonn Application filed October 6, 1927. Serial No. 224,468.

This invention relates to electrical reproducers and has for its principal ob ect the provision of a simple and efficient device up or reproducer may be plugged into the radio circuit which is automatically reconnected for radio reception when the plug is ill the provision of an electric circuit whereby one of the pick-up leads is inserted between the grid leak and the detector tube whereby the detector tube may be utilized an amplifier tube, the grid leak and condenser being substantially eliminated from the circuitelectricallywithout in any way interfering with their function in the ordinary use of the device for radio reception.

"- A still further object of the present i11- ventioncontemplates the use of a jack in the radio set thru which by a suitable plug the reproducer or pick-up may be electrically connected to the amplifying portion of the radio set, automatically disconnecting the plate of the detector tube from the primary of the first audio tube. i

While it is a very simple matterto design a radio receiver so that thegrooves in a phonograph disk will operate to produce changes of electric current which may readily be amplified in ordinary fashion, devices of this kind have never gone into wide commercial use because of the trouble and nuisance in making the con nections or because of the quite unnecessary expense of having a separate and distinct audio set for the phonograph which obviously wouldscarcely ever be used at the same time that radio music is beingreceived.

In the drawings: a V

Figure l shows a simple embodiment of the invention. l y

Figure 2 shows a modified form of connection.

Figure 3 shows a circuit in which the pickwithdrawn.

Figure 4 shows a modification.

The pick-up has a casing 10, preferably of a phenol condensation product, which is a cup-shaped shell having an integral tubular extension 11 readily and snugly fitting upon the tone arm of a phonograph. While I much prefer that this casing be readily detachable it may 0b viously be permanently secured to the tone arm and the latter may or may not be readily detachable.v Within the casing is a reproducer unit including a coil 15, the terminals of which are connected to binding posts 16 and 17 which receive the tips of theconnecting cord 18 which passes thru a hole such as- 19 in the rear of the casing. The spool is secured between channel pieces 22 and 23 which are secured to the pole pieces 20 and 21 of apermanentmagnet The channel 23 isriveted or otherwise secured to the face plate 25 and supports the magnet and coil. Tl1e screw 24L holds the binding posts 16 and 17 in place on the face plate.

The armature 26 is a flat piece of soft 117011 pivoted centrally of the coil 15 and urged to one side by the gum rubber damper 28. The front plate 25 which carries the magnet, the coil and all parts within the casing 10, is secured to the casing by screws such as 30 which also hold in place the light metal guard 32 shielding the vibrating; lever 35 which rests against a damping soft rubber disk 37 The lever 35 is connected to the armature 26 by a light arm 38, the two rubber dampers 37 and 28 acting.v as will be noted, on opposite sides of the disk and substantially neutralizing each otheras faras moving the armature is concerned but acting additively, in damping. The vibratinglever 35 is pivoted to the face plate 25 preferably by pressing the bracket 38. to which is per manently secured both the lever and the needle carrier 40, against the knife edge lugs ll ofthe faceplate bymeans of springs 42, the tension of which may be adjusted by meansof the screws 14. I find it highly lined with a soft rubber ring advantageous to insert damping bits of soft rubber 45 under each end of each spring.

The cord 18 from the binding posts 16 and 17 leads to the radio set, a very convenient method of attachment being as shown in Figure 4, one wire of cord 18 such as 5-0 connecting into the radio circuit between the grid and the grid leak and the other wire such as 51 being connected to the A battery, preferably 011 the negative side for in this way the detector tube acts to amplify the current from the pick-up. A convenient method of making the connection is shown in Figure 1, 53 being the grid condenser, 5d the grid leak and 55 the spring clip which sup ports the grid leak when one of the type shown is used. The wire 50, having a switch 56. therein, leads to a metal cone 5'? which fits on the end of the grid leak 5a. In the actual construction it is preferable to have an extra U-shape terminal such as 58 which is used when the set does not have the elongated tubular grid leak such as 54 but uses a variable leak. The wire 51 also has a regulation U-shaped terminal 59 which may be connected directly to the A battery. Between the cord 18 and the wires 50 and 51 I provide a small case 60 containing a bypass condenser 61 of approximately one microfarad and a variable resistance 62 of about seventy- 1V0 kilohms. This case is a standard unit and is not essential in most cases since no blocking condenser is needed in the hook-up of Figure 1 but is needed in case the reproducer is connected to the plate terminal of the detector tube instead of to the grid terminal as preferred.

A very simple form of connection includes the use of a disk (Figure 2) containing four holes to receive the prongs of a standard UX tube. In one of the holes for the filament terminals such as the one receiving the prong 71 and either the plate or the grid hole, are placed contacts 73 which touch the tube prongs and the wires 50 and 51 are connected to these contacts. The device is very similar to the ordinary adaptor, particularly those with power tube connections and external leads. This disk TO'slips on the base of the detector tube and leads are sufiiciently small and flexible to fit easily between the tube and the old-fashioned socket should the latter be used.

Referring now particularly to Figure 3. 80 is the detector tube and 82 is the rimary winding of the first audio transformer which is connected to the outside terminals 83 and 84: of a jack, the inside terminals 85 and 86 being connected respectively to the plate of the detector and to the positive side of the detector B battery. When the plug is not in the jack the device acts as a straight radio receiver. the detector plate being connected to the plus side of the B battery providing the proper voltage for the detector tube,

thru the primary winding of the first audio in the usual fashion. In this hook-up the two wires 88 from the pickup lead to a modulator plug 89 which is a standard article of commerce and intended generally to control the volume of loud speakers and contains a variable resistance controlled by a knob 90.

By inserting the plug 89 in the jack the reproducer is connected into the amplifying portion of the radio set and the detector tube is disconnected by the breaking of the current between the contacts 83 and 85. This hookup is very similar in effect to that had by providing a prong carrying member readily insertable into the detector tube socket to engage a filament and the plate spring contacts, but is much neater in looks and is very much less trouble particularly since in all old style sets the jack described is already in place in the set and is intended for the re ception of the head piece plug except that the connections are reversed. In transforming an old-fashioned set nothing whatsoever need be done save the changing of the jack terminals, that is, connecting the first audio to the outside terminals instead of to the inside as the sets are ordinarily wired.

In Figure l I have shown the hook-up used in Figure 1 or in connection with the disk 70 of Figure 2. The detector tube is 80, the primary of the first audio is 82, the grid leak is 54, the grid condenser is 53. One prong of the jack 91 is connected to the side of the grid leak nearest the tube as more clearly shown in Figure 1 and the other terminal is connected to the lead from the negative side 93 of the A battery. The wires 50 and 51 are connected to a plug 95 which when inserted in the jack 91 connects the reproducer as indicated. In this hook-up I have again shown my standard case 60 with the condens-' er and variable resistance but obviously the reproducer may be hooked to the plug of a standard modulator as shown in Figure 3. The condenser 61 is not objectionable however, and is quite essential where the connection is made to the plate of the detector instead of to the grid.

hat I claim is:

1. A connecting means for electrically connecting a. telegraphophone sound box with a radio receiver consisting of a metal cone adapted to be inserted between a conical ended grid leak and its holder.

2. A connecting means for electrically connecting a telegraphophone sound box with a radio receiver, said means including a terminal held in place between the grid leak and its holding device which terminal is not removed when the radio receiver is used for its normal function of receiving radio signals.

In testimony whereof I afiix my signature.

LE ROY J. LEISPIMAN. 

